The symbols of dark water or a dark lake are pertinent because they give some clue to the actual emotion that is involved in the process. A dream about one of these symbols may seem perplexing at first but after understanding their close relation to the human emotional spectrum it should not be that difficult to interpret.
To dream of dark water means you are thinking about endlessness and complexity of life and emotion. Water is known notoriously for symbolizing all kinds of different emotions and feelings. Water symbolizes the entire breadth of emotional feelings that you can have about something so to dream about dark water means that you feel like you can't really predict your emotions at this time.
You are having unpredictable feelings and you want to know how to work through this period. Sometimes the best way to get through a period like this is to just wait out whatever it is that is causing you to feel this way. There is usually some reason for a dream like this, something that is holding you back all on its own, and it makes sense for you to think this way. If you have a dream in which you see dark water you are just having trouble sorting through your feelings on some subject and you need a little assistance.
If you have a dream about a dark lake then this means that you are focused on the complexity of emotion in your world right now. You are thinking about the depth of thought that you have and all of the different things that set that off. Water symbolizes emotion, feeling, and depth. To dream of a dark lake means that your emotions are a bit confused right now and it is hard to make head or tails of them. You aren't even sure of your own feelings, but give it time and it should all come to you.